This invention relates to an apparatus for the external fixation and stabilization of a bone fracture. The invention is also concerned with a method for the external fixation and stabilization of a bone fracture utilizing said apparatus.
The setting of fractured bones has been practiced since ancient times and various types of splints and other external fixation devices have been used through the ages. In more recent times, particularly with the advent of X-rays, the art of fixation and stabilization of bone fractures has become more and more precise. Modern devices include surgical pins to hold the bone fragments and various arrangements for clamping or locking the pins to some external bar or framework whereby said bone fragments are held together until the fracture is healed.
One type of apparatus involving pin-holder assemblies is disclosed in U.S. Pat. No. 4,127,119 issued Nov. 28, 1978 to Kronner. The Kronner Circular Compression Frame comprises pins for penetrating bone segments, first and second pin holder assemblies adapted to receive said pins and elongate connector assemblies for coupling said pin holder assemblies.
U.S. Pat. No. 4,312,336 issued Jan. 26, 1982 to Danieletto et al discloses an external axial fixation unit comprising an elongate central body member comprised of two parts adapted to be mutually displaceable parallel to the longitudinal axis of said member and rotatably fixed with respect to each other. The member supports a clamping device for pins adapted to be inserted into a bone segment and the member further includes a pressing and tensioning device. The unit is available commercially under the Trademark Orthofix.
U.S. Pat. No. 4,273,116 issued June 16, 1981 to Claude Chiquet, discloses an external fixation device comprising a plurality of sliding universal articulated couplings for adjustment and locking of connections between pins and tubular tie-rods. Each of said couplings essentially includes a T-shaped member having two arms with longitudinal slots; two nut-and-bolt assemblies disposed in said slots; cooperating clamping means for adjustably clamping pins to said two arms, a spherical adapter sleeve split by staggered slots and slidingly mounted on said tie-rod; a coupling locking clamp and a further nut-and-bolt assembly for securing the device.
The above-described prior art devices are of varying complexity and it has now been found that comparable fixation and stability may be achieved by an apparatus in which the attachment of the bone-piercing pins to the component which establishes fixation and stability is by way of a novel clamp member which allows substantially universal adjustment and fixation of the pins and in which said component is a rigid bar having predetermined torsional, flexural and axial stiffness characteristics, which characteristics may be chosen according to the state of healing of the fracture.
Additional stabilization may be achieved by the addition of one or more further rigid bars, each of said bars being attached to each other bar by a novel clamp comprising two separatable portions adjustably connected to each other through a taper lock.
In an alternative embodiment of the invention said taper lock clamp may be used to couple a pin to a rigid bar as part of a modified apparatus comprising a plurality of such couplings.